Biology subjects

Sengupta, P.

Publications and source records attributed to Sengupta, P..

At least 37 records · Page 2Linked to original sources

bioRxiv2023

Molecular encoding of stimulus features in a single sensory neuron type enables neuronal and behavioral plasticity

Neurons modify their transcriptomes in response to an animals experience. How specific experiences are transduced to modulate gene expression and precisely tune neuronal functions are not fully defined. Here, we describe the molecular profile of a thermosensory neuron pair in C. elegans experiencing different temperature stimuli. We find that distinct salient features of the temperature stimulus including its duration, magnitude of change, and absolute value are encoded in the gene expression program in this single neuron, and identify a novel transmembrane protein and a transcription factor whose specific transcriptional dynamics are essential to drive neuronal, behavioral, and developmental plasticity. Expression changes are driven by broadly expressed activity-dependent transcription factors and corresponding cis-regulatory elements that nevertheless direct neuron- and stimulus-specific gene expression programs. Our results indicate that coupling of defined stimulus characteristics to the gene regulatory logic in individual specialized neuron types can customize neuronal properties to drive precise behavioral adaptation.

neuroscience↗

bioRxiv2022

Developmental history modulates adult olfactory behavioral preferences via regulation of chemoreceptor expression in C. elegans

Developmental experiences play critical roles in shaping adult physiology and behavior. We and others previously showed that adult C. elegans which transiently experienced dauer arrest during development (PD: post-dauer) exhibit distinct gene expression profiles as compared to control adults which bypassed the dauer stage. In particular, the expression patterns of subsets of chemoreceptor genes are markedly altered in PD adults. Whether altered chemoreceptor levels drive behavioral plasticity in PD adults is unknown. Here we show that PD adults exhibit enhanced attraction to a panel of food-related attractive volatile odorants including the bacterially-produced chemical diacetyl. Diacetyl-evoked responses in the AWA olfactory neuron pair are increased in both dauer larvae and PD adults, and we find that these increased responses are correlated with upregulation of the diacetyl receptor ODR-10 in AWA likely via both transcriptional and post-transcriptional mechanisms. We show that transcriptional upregulation of odr-10 expression in dauer larvae is in part mediated by the DAF-16 FOXO transcription factor. Via transcriptional profiling of sorted populations of AWA neurons from control and PD adults, we further show that the expression of a subset of additional chemoreceptor genes in AWA is regulated similarly to odr-10 in PD animals. Our results suggest that developmental experiences may be encoded at the level of olfactory receptor regulation, and provide a simple mechanism by which C. elegans is able to precisely modulate its behavioral preferences as a function of its current and past experiences.

neuroscience↗

bioRxiv2022

Neuronal temperature perception induces specific defenses that enable C. elegans to cope with the enhanced reactivity of hydrogen peroxide at high temperature

Hydrogen peroxide is the most common reactive chemical that organisms face on the microbial battlefield. The rate with which hydrogen peroxide damages biomolecules required for life increases with temperature, yet little is known about how organisms cope with this temperature-dependent threat. Here, we show that Caenorhabditis elegans nematodes use temperature information perceived by sensory neurons to cope with the temperature-dependent threat of hydrogen peroxide produced by the pathogenic bacterium Enterococcus faecium. These nematodes preemptively induce the expression of specific hydrogen peroxide defenses in response to perception of high temperature by a pair of sensory neurons. These neurons communicate temperature information to target tissues expressing those defenses via an insulin/IGF1 hormone. This strategy, which we call "enhancer sensing," is the first example of a multicellular organism inducing their defenses to a chemical when they sense an inherent enhancer of the reactivity of that chemical.

neuroscience↗

bioRxiv2021

Context-dependent inversion of the response in a single sensory neuron type reverses olfactory preference behavior

The valence and salience of individual odorants are modulated by an animals innate preferences, learned associations, and internal state, as well as by the context of odorant presentation. The mechanisms underlying context-dependent flexibility in odor valence are not fully understood. Here we show that the behavioral response of C. elegans to bacterially-produced medium-chain alcohols switches from attraction to avoidance when presented in the background of a subset of additional attractive chemicals. This context-dependent reversal of odorant preference is driven by cell-autonomous inversion of the response to alcohols in the single AWC olfactory neuron pair. We find that while medium-chain alcohols inhibit the AWC olfactory neurons to drive attraction, these alcohols instead activate AWC to promote avoidance when presented in the background of a second AWC-sensed odorant. We show that these opposing responses are driven via engagement of different odorant-directed signal transduction pathways within AWC. Our results indicate that context-dependent recruitment of alternative intracellular signaling pathways within a single sensory neuron type conveys opposite hedonic valences, thereby providing a robust mechanism for odorant encoding and discrimination at the periphery.

neuroscience↗

bioRxiv2021

xbx-4, a homolog of the Joubert syndrome gene FAM149B1, acts via the CCRK and MAK kinase cascade to regulate cilia morphology

Primary cilia are microtubule (MT)-based organelles that mediate sensory functions in multiple cell types. Disruption of cilia structure or function leads to a diverse collection of diseases termed ciliopathies (1-3). Mutations in the DUF3719 domain-containing protein FAM149B1 have recently been shown to elongate cilia via unknown mechanisms and result in the ciliopathy Joubert syndrome (4). The highly conserved CCRK and MAK/RCK kinases negatively regulate cilia length and structure in Chlamydomonas, C. elegans, and mammalian cells (5-11). How the activity of this kinase cascade is tuned to precisely regulate cilia architecture is unclear. Here we identify XBX-4, a DUF3719 domain-containing protein related to human FAM149B1, as a novel regulator of the DYF-18 CCRK and DYF-5 MAK kinase pathway in C. elegans. As in dyf-18 and dyf-5 mutants (11), sensory neuron cilia are elongated in xbx-4 mutants and exhibit altered axonemal MT stability. XBX-4 promotes DYF-18 CCRK activity to regulate DYF-5 MAK function and localization. We find that Joubert syndrome-associated mutations in the XBX-4 DUF3719 domain also elongate cilia in C. elegans. Our results identify a new metazoan-specific regulator of this highly conserved kinase pathway, and suggest that FAM149B1 may similarly act via the CCRK/MAK kinase pathway to regulate ciliary homeostasis in humans.

cell biology↗

bioRxiv2021

Vacuole phase-partitioning boosts mitochondria activity and cell lifespan through an inter-organelle lipid pipeline

Functional linkage between mitochondria and lysosomes is crucial for survival under starvation and lifespan extension. Despite such co-dependency, the supportive pathways connecting mitochondria and lysosomes remain unclear. Here, we identify an inter-organelle lipid trafficking pathway linking yeast vacuole and mitochondria that results in increased mitochondria growth and respiratory activity under glucose starvation. The pathway depends on vacuolar phase-separated, lipid domains, which provide zones for: activation of the vacuolar proton pump; lipid droplet (LD) docking and internalization; and, lipid transfer from vacuole-to-ER-to-mitochondria. Partitioned vacuolar domains form through a specialized type of macro-autophagy, triggered only under acute glucose starvation, that delivers sterol-rich, endosomal-derived lipids to the vacuole. To balance this lipid influx, the vacuole reroutes lipids back to the ER to support both LD biogenesis and mitochondria growth and activity. Energy produced by enhanced mitochondrial activity then feeds back to support the inter-organelle lipid trafficking pathways to ensure survival under nutrient stress.

cell biology↗

bioRxiv2020

Ciliary neuropeptidergic signaling dynamically regulates excitatory synapses in postnatal neocortical pyramidal neurons

Primary cilia are compartmentalized sensory organelles present on the majority of neurons in the mammalian brain throughout adulthood. Recent evidence suggests that cilia regulate multiple aspects of neuronal development, including the maintenance of neuronal connectivity. However, whether ciliary signals can dynamically modulate postnatal circuit excitability is unknown. Here we show that acute cell-autonomous knockdown of ciliary signaling rapidly strengthens glutamatergic inputs onto cultured neocortical pyramidal neurons, and increases spontaneous firing. This increased excitability occurs without changes to passive neuronal properties or intrinsic excitability. Further, the neuropeptide receptor somatostatin receptor 3 (SSTR3) is localized nearly exclusively to excitatory neuron cilia both in vivo and in culture, and pharmacological manipulation of SSTR3 signaling bidirectionally modulates excitatory synaptic inputs onto these neurons. Our results indicate that ciliary neuropeptidergic signaling dynamically modulates excitatory synapses, and suggest that defects in this regulation may underlie a subset of behavioral and cognitive disorders associated with ciliopathies.

neuroscience↗

bioRxiv2020

Girdin regulates dendrite morphogenesis and cilium position in two specialized sensory neuron types in C. elegans

Primary cilia are located at the dendritic tips of sensory neurons and house the molecular machinery necessary for detection and transduction of sensory stimuli. The mechanisms that coordinate dendrite extension with cilium position during sensory neuron development are not well understood. Here, we show that GRDN-1, the Caenorhabditis elegans ortholog of the highly conserved scaffold and signaling protein Girdin/GIV, regulates both cilium position and dendrite extension in the postembryonic AQR and PQR gas-sensing neurons. Mutations in grdn-1 disrupt dendrite outgrowth and mislocalize cilia to the soma or proximal axonal segments in AQR, and to a lesser extent, in PQR. GRDN-1 is localized to the basal body and regulates localization of HMR-1/Cadherin to the distal AQR dendrite. However, loss of HMR-1 and/or SAX-7/LICAM, molecules previously implicated in sensory dendrite development in C. elegans, do not alter AQR dendrite morphology or cilium position. We demonstrate that GRDN-1 localization in AQR is regulated by UNC-116/Kinesin-1, and that correspondingly, unc-116 mutants exhibit severe AQR dendrite outgrowth and cilium positioning defects. In contrast, GRDN-1 and cilium localization in PQR is modulated by LIN-44/Wnt signaling. Together, these findings identify upstream regulators of GRDN-1, and describe new cellspecific roles for this multifunctional protein in sensory dendrite development.

developmental biology↗

bioRxiv2020

Nanoencapsulation of clove oil and study of physico-chemical properties, cytotoxic, haemolytic and antioxidant activities

The therapeutic properties of clove oil is known for centuries, however, the pungent nature, chemical instability and low water solubility impose limitations in harnessing its therapeutic potential. Hence, nanoencapsulation of clove oil was performed to overcome the above constraints and control its in-vitro release. The stability of nanoemulsion depends on various factors where the surfactant and its hydrophile/lipofile balance (HLB) play a key role. The non-ionic surfactants Tween 20, 40 and 80 with HLB of 16.7, 15.6 and 15, respectively, were used to study the stability of clove oil nanoemulsion (CON). The creaming index of CON prepared with Tween 20, 40 and 80 was 22.75 and 17.5 and 1.5%, respectively, after 8 days of storage at room temperature. Tween 20 and 40 produced particles > 300 nm while Tween 80 resulted in particles of size [~]150 nm. Transmission electron microscopic image of spray dried CON prepared with Tween 80 showed particle size in the range 150-190 nm after one month of storage at room temperature. The in vitro release studies showed 76% and 42% cumulative release of CON and native clove oil (NC), respectively at pH 7.4. The cellular toxicity of CON was significantly reduced by four fold compared to NC at a concentration of 60 {micro}g/mL when tested on Caco2 cells. Similarly, haemolytic activity on red blood cells revealed less than 10% haemolysis signifying the compatibility of CON for its nutraceutical applications. In addition, CON also exhibited higher in-vitro antioxidant compared to NC as shown by DPPH and ABTS radical scavenging activity. Collectively, we have developed a unique method for NC nanoencapsulation using cost effective polysaccharide (maltodextrin) and surfactant for stabilizing the nanoemulsion for increased bioactivity.

cell biology↗

bioRxiv2020

CREB mediates the C. elegans dauer polyphenism through direct and cell-autonomous regulation of TGF-β expression

Animals can adapt to dynamic environmental conditions by modulating their developmental programs. Understanding the genetic architecture and molecular mechanisms underlying developmental plasticity in response to changing environments is an important and emerging area of research. Here, we show a novel role of cAMP response element binding protein (CREB)-encoding crh-1 gene in developmental polyphenism of C. elegans. Under conditions that promote normal development in wild-type animals, crh-1 mutants inappropriately form transient pre-dauer (L2d) larva and express the L2d marker gene. L2d formation in crh-1 mutants is specifically induced by the ascaroside pheromone ascr#5 (asc-{omega}C3; C3), and crh-1 functions autonomously in the ascr#5-sensing ASI neurons to inhibit L2d formation. Moreover, we find that CRH-1 directly binds upstream of the daf-7 TGF-{beta} locus and promotes its expression in the ASI neurons. Taken together, these results provide new insight into how animals alter their developmental programs in response to environmental changes.

developmental biology↗

bioRxiv2020

Integrated Bioinformatics Analysis Deciphering the microRNA Regulation in Protein-Protein Interaction Network in Lung Adenocarcinoma

BackgroundThe architecture of the protein-protein interaction (PPI) network in any organism relies on their gene expression signature. microRNAs (miRNAs) have recently emerged as major post transcriptional regulators that control PPI by targeting mainly untranslated regions of the gene encoding proteins. Here, we aimed to unveil the role of miRNAs in the PPI network for identifying potential molecular targets for lung adenocarcinoma (LUAD). Materials and methodsThe expression profiles of miRNAs and mRNAs were collected from the NCBI Gene Expression Omnibus (GEO) database (GSE74190 and GSE116959). Abnormally expressed mRNAs from the data were appointed to construct a PPI network and hence incorporated with the miRNA-mRNA regulatory network. The miRNAs and mRNAs in this network were subjected to functional enrichment. Through the network analysis, hubs were identified and their mutation rate and probability of cooccurrence were calculated. ResultsWe identified 17 miRNAs and 429 mRNAs signature for differentially altered transcriptome in LUAD. The combined miRNA-mRNA regulatory network exhibited scale-free characteristics. Network analysis showed 5 miRNA (including hsa-miR-486-5p, hsa-miR-200b-5p, and hsa-miR-130b-5p) and 10 mRNA (including ASPM, CCNB1, TTN, TPX2, and BIRC5) which expressively contribute in the LUAD. We further investigated the hub genes and noticed that ASPM and TTN had the maximum rate of mutation and possessed a high tendency of cooccurrence in LUAD. ConclusionThis study provides a unique network approach to the exploration of the underlying molecular mechanism in LUAD. Identified mRNAs and miRNAs may therefore, serve as significant prognostic predictors and therapeutic targets.

bioinformatics↗

bioRxiv2020

Feeding state functionally reconfigures a sensory circuit to drive thermosensory behavioral plasticity

Internal state alters sensory behaviors to optimize survival strategies. The neuronal mechanisms underlying hunger-dependent behavioral plasticity are not fully characterized. Here we show that feeding state regulates C. elegans negative thermotaxis behavior by engaging a modulatory circuit whose activity gates the output of the core thermotaxis network. Feeding state does not alter the activity of the core thermotaxis circuit comprised of AFD thermosensory and AIY interneurons. Instead, prolonged food deprivation potentiates temperature responses in the AWC sensory neurons, which inhibit the postsynaptic AIA interneurons to override and disrupt AFD-driven thermotaxis behavior. Acute inhibition and activation of AWC and AIA, respectively, restores negative thermotaxis in starved animals. We find that state-dependent modulation of AWC-AIA temperature responses requires INS-1 insulin-like peptide signaling from the gut and DAF-16 FOXO function in AWC. Our results describe a mechanism by which functional reconfiguration of a sensory network via gut-brain signaling drives state-dependent behavioral flexibility.

neuroscience↗

bioRxiv2020

An antagonistic driver of the microbial phyllosphere suppresses infection of Arabidopsis thaliana by the oomycete pathogen Albugo laibachii via a secreted hydrolase

Plants are not only challenged by pathogenic organisms, but also colonized by commensal microbes. The network of interactions these microbes establish with their host and amongst each other is suggested to contribute to the immune responses of plants against pathogens. In wild Arabidopsis thaliana populations, the oomycete pathogen Albugo laibachii has been shown to play an influential role in structuring the leaf phyllosphere. We show that the epiphytic yeast Moesziomyces bullatus ex Albugo on Arabidopsis, a close relative of pathogenic smut fungi, is an antagonistic member of the A. thaliana phyllosphere, which reduces infection of A. thaliana by A. laibachii. Combination of transcriptome analysis, reverse genetics and protein characterization identified a GH25 hydrolase with lysozyme activity as the major effector of this microbial antagonism. Our findings broaden the understanding of microbial interactions within the phyllosphere, provide insights into the evolution of epiphytic basidiomycete yeasts and pave the way for the development of novel biocontrol strategies.

microbiology↗

bioRxiv2019

Modulation of sensory behavior and food choice by an enteric bacteria-produced neurotransmitter

Animals coexist in commensal, pathogenic or mutualistic relationships with complex communities of diverse organisms including microbes1. Some bacteria produce bioactive neurotransmitters which have been proposed to modulate host nervous system activity and behaviors2. However, the mechanistic basis of this microbiota-brain modulation and its physiological relevance is largely unknown. Here we show that in C. elegans, the neuromodulator tyramine (TA) produced by gut-colonizing commensal Providencia bacteria can bypass the requirement for host TA biosynthesis to manipulate a host sensory decision. Bacterially-produced TA is likely converted to octopamine (OA) by the host tyramine beta-hydroxylase enzyme. OA, in turn, targets the OCTR-1 receptor on the ASH/ASI sensory neurons to modulate an aversive olfactory response. We identify genes required for TA biosynthesis in Providencia, and show that these genes are necessary for modulation of host behavior. We further find that C. elegans colonized by Providencia preferentially select these bacteria in food choice assays, and that this selection bias requires bacterially-produced TA. Our results demonstrate that a neurotransmitter produced by gut microbiota mimics the functions of the cognate host molecule to override host control of a sensory decision, thereby promoting fitness of both host and microbe.

neuroscience↗

bioRxiv2019

ER membranes exhibit phase behavior at sites of organelle contact

The plasma membrane of cells exhibits phase behavior that allows transient concentration of specific proteins and lipids, giving rise to functionally dynamic and diverse nanoscopic domains. This phase behavior is observable in giant plasma membrane-derived vesicles, in which microscopically visible, liquid-ordered (Lo) and liquid-disordered (Ld) lipid domains form upon a shift to low temperatures. The extent such phase behavior exists in the membrane of the endoplasmic reticulum (ER) of cells remains unclear. To explore the phase behavior of the ER membrane in cells, we used hypotonic cell swelling to generate Large Intra-Cellular Vesicles (LICVs) from the ER in cells. ER LICVs retained their lumenal protein content, could be retubulated into an ER network, and maintained stable inter-organelle contacts, where protein tethers are concentrated at these contacts. Notably, upon temperature reduction, ER LICVs underwent reversible phase separation into microscopically-visible Lo and Ld lipid domains. The Lo lipid domains marked ER contact sites with other organelles. These findings demonstrate that LICVs provide an important model system for studying the biophysical properties of intracellular organelles in cells.\n\nSignificance StatementPrior work has demonstrated that the plasma membrane can phase separate into microscopically visible Lo and Ld domains with distinct lipid and protein content. However, such behavior on the ER membrane has not been experimentally observed, even though the ER contacts every organelle of the cell, exchanging lipids and metabolites in a highly regulated manner at these contacts. We find here that hypotonic treatment generates Large Intra-Cellular Vesicles from the endoplasmic reticulum and other membrane-bound organelles in cells, enabling the study of phase behavior on the ER membrane. We show that ER membranes can be reversibly phase separated into microscopically-observable, Lo and Ld domains. ER LICVs also maintained stable inter-organelle contact sites in cells, with organelle tethers concentrated at these contacts.

biophysics↗

bioRxiv2019

The C. elegans Tubby homolog dynamically modulates olfactory cilia membrane morphogenesis and phospholipid composition

Plasticity in sensory signaling is partly mediated via regulated trafficking of signaling molecules to and from primary cilia. Tubby-related proteins regulate ciliary protein transport; however, their roles in remodeling of cilia properties are not fully understood. We find that the C. elegans TUB-1 Tubby homolog regulates membrane morphogenesis and signaling protein transport in specialized sensory cilia. In particular, TUB-1 is essential for sensory signaling-dependent reshaping of olfactory cilia morphology. We show that compromised sensory signaling alters cilia membrane phosphoinositide composition via TUB-1-dependent trafficking of a PIP5 kinase. TUB-1 regulates localization of this lipid kinase at the cilia base in part via localization of the AP-2 adaptor complex subunit DPY-23. Our results describe new functions for Tubby proteins in the dynamic regulation of cilia membrane lipid composition, morphology, and signaling protein content, and suggest that this conserved family of proteins plays a critical role in mediating cilia structural and functional plasticity.

cell biology↗

bioRxiv2017

Optical excitation and detection of neuronal activity

Optogenetics has emerged as an exciting tool for manipulating neural activity, which in turn, can modulate behavior in live organisms. However, detecting the response to the optical stimulation requires electrophysiology with physical contact or fluorescent imaging at target locations, which is often limited by photobleaching and phototoxicity. In this paper, we show that phase imaging can report the intracellular transport induced by optogenetic stimulation. We developed a multimodal instrument that can both stimulate cells with subcellular spatial resolution and detect optical pathlength changes with nanometer scale sensitivity. We found that optical pathlength fluctuations following stimulation are consistent with active organelle transport. Furthermore, the results indicate a broadening in the transport velocity distribution, which is significantly higher in stimulated cells compared to optogenetically inactive cells. It is likely that this label-free, contactless measurement of optogenetic response will provide an enabling approach to neuroscience.\n\nO_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY Quantitative phase imaging enables label-free detection of enhanced intracellular activities induced by optogenetic stimulation.\n\nC_FIG_DISPLAY

bioengineering↗

bioRxiv2017

Rictor/TORC2 mediates gut-to-brain signaling in the regulation of phenotypic plasticity in C. elegans

Animals integrate external cues with information about internal conditions such as metabolic state to execute the appropriate behavioral and developmental decisions. Information about food quality and quantity is assessed by the intestine and transmitted to modulate neuronal functions via mechanisms that are not fully understood. The conserved Target of Rapamycin complex 2 (TORC2) controls multiple processes in response to cellular stressors and growth factors. Here we show that TORC2 coordinates larval development and adult behaviors in response to environmental cues and feeding state in the bacterivorous nematode C. elegans. During development, pheromone, bacterial food, and temperature regulate expression of the daf-7 TGF-{beta} and daf-28 insulin-like peptide in sensory neurons to promote a binary decision between reproductive growth and entry into the alternate dauer larval stage. We find that TORC2 acts in the intestine to regulate neuronal expression of both daf-7 and daf-28, which together reflect bacterial-diet dependent feeding status, thus providing a mechanism for integration of food signals with external cues in the regulation of neuroendocrine gene expression. In the adult, TORC2 similarly acts in the intestine to modulate food-regulated foraging behaviors via the PDFR-1 neuropeptide receptor. We also demonstrate that genetic variation affects food-dependent larval and adult phenotypes, and identify quantitative trait loci (QTL) associated with these traits.Together, these results suggest that TORC2 acts as a hub for communication of feeding state information from the gut to the brain, thereby contributing to modulation of neuronal function by internal state.\n\nAUTHOR SUMMARYDecision-making in all animals, including humans, involves weighing available information about the external environment as well as the animals internal conditions. Information about the environment is obtained via the sensory nervous system, whereas internal state can be assessed via cues such as levels of hormones or nutrients. How multiple external and internal inputs are processed in the nervous system to drive behavior or development is not fully understood. In this study, we examine how the nematode C. elegans integrates dietary information received by the gut with environmental signals to alter nervous system function. We have found that a signaling complex, called TORC2, acts in the gut to relay nutrition signals to alter hormonal signaling by the nervous system in C. elegans. Altered neuronal signaling in turn affects a food-dependent binary developmental decision in larvae, as well as food-dependent foraging behaviors in adults. Our results provide a mechanism by which animals prioritize specific signals such as feeding status to appropriately alter their development and/or behavior.

neuroscience↗